Laser-induced microexplosion confined in the bulk of a sapphire cystal: Evidence of multimegabar pressures

Extremely high pressures (∼10TPa) and temperatures (5×105K) have been produced using a single laser pulse (100nJ, 800 nm, 200 fs) focused inside a sapphire crystal. The laser pulse creates an intensity over 1014W/cm2 converting material within the absorbing volume of ∼0.2μm3 into plasma in a few fs. A pressure of ∼10TPa, far exceeding the strength of any material, is created generating strong shock and rarefaction waves. This results in the formation of a nanovoid surrounded by a shell of shock-affected material inside undamaged crystal. Analysis of the size of the void and the shock-affected zone versus the deposited energy shows that the experimental results can be understood on the basis of conservation laws and be modeled by plasma hydrodynamics. Matter subjected to record heating and cooling rates of 1018K/s can, thus, be studied in a well-controlled laboratory environment.